The present invention relates to a magnetic head device for use in combination with a floppy disk drive apparatus and, more particularly, to a magnetic head device which can read and write data with different electromagnetic conversion characteristics and can, therefore, read data from, and write data on, floppy disks of different recording densities.
A floppy disk drive apparatus has compatibility with respect to floppy disks of the same size. Recently, a recording density of floppy disks has been highly increased, so that floppy disks with a high recording density and those with a low recording density are both present. Since these floppy disks have compatibility, they can be used in a single floppy disk drive apparatus. In this case, data is written on or read from the floppy disks by a magnetic head device having a single read/write gap.
A magnetic head device of a floppy disk drive apparatus can be roughly classified into a tunnel erase head and a straddle head in accordance with the head structure. A magnetic head device of the tunnel erase head type can be further classified into a laminate type and a bulk type. Conventional magnetic head devices include a core having a single read/write gap regardless of the type, and a gap length of the read/write gap is constant. Therefore, data is written on or read from various floppy disks with different recording densities by the single read/write gap having the constant gap length. However, an optimal gap length exists in accordance with each of different recording densities of disks. In general, as a recording density of a floppy disk is increased, an optimal gap length for the density is reduced. Conventional magnetic head device have only a single read/write gap, and a gap length of the read/write gap is set optimal for a floppy disk with either a high or low density or for a floppy disk with a representative recording density between the high and low densities. For example, when a gap length of a read/write gap is set optimal for a disk with a low recording density, the magnetic head device reads data from or writes data on a disk by the use of this read/write gap for a disk with a high recording density, so that the magnetic head device cannot read and write data with optimal conversion characteristics for the disk with a high recording density. Especially as recording density of floppy disks is increased, a difference between a gap length optimal for a floppy disk loaded in the apparatus and a gap length set in the magnetic head device is increased. For this reason, in a conventional magnetic head device, as the difference between the two gap lengths is increased, resolution and electromagnetic conversion characteristics in a read/write operation are degraded. Therefore, it is difficult to perform an optimal read/write operation.